This program is designed to study oxygenation of blood and tissues and the effects of lung disease on the pulmonary and systemic circulations. The functional and structural abnormalities in diffuse interstitial lung diseases will be examined, particularly with regard to gas exchange, hemodynamics, and the effects of therapy. Serial studies of respiratory muscle strength in patients with chronic lung diseases, neuromuscular diseases, and chest wall abnormalities will be made to determine the contribution of respiratory muscle dysfunction to development of hypercapneic respiratory failure. The oxygen transport function of muscle myoglobin in myocardial performance and the interaction with muscle mitochondria will be investigated. Intravenous administration of Fab fragments of antibody specific for angiotensin converting enzyme will be tested for its anticatalytic activity in vivo. To pursue these studies a large scale preparation of the purified converting enzyme will be undertaken. Cultured endothelial cells will be studied to examine the specific features of beta-adrenergic receptors in these cells. BIBLIOGRAPHIC REFERENCES: Caldwell, P.R.B., B.C. Seegal, K.C. Hsu, M. Das and R.L. Soffer.: Angiotensin-converting enzyme: Vascular endothelial localization. Science 191:1050-51, 1976. Caldwell, P.R.B., H.J. Wigger, M. Das and R.L. Soffer: Angiotensin-converting enzyme: Effect of antienzyme antibody in vivo. FEBS Letters 63:82-84, 1976.